Comment by reducesuffering

Sam Altman has written, and probably still believes,

"Development of superhuman machine intelligence (SMI) is probably the greatest threat to the continued existence of humanity."[0]

This means he acknowledges that his actions have the potential to kill every human family on Earth. It should be of no surprise that people took his beliefs seriously.

[0] https://blog.samaltman.com/machine-intelligence-part-1